Im two sessions in to the game, and I've already noticed some issues. There's a lot of words here. First, the purely technical, issues with the book itself, not the game:

1. The first combat, we actually missed a lot of rules, though not really ones that would have changed the outcome much. Notably, we missed the rule about excess Flow turning into money, because it was printed in that orange gradient, over a background of a very similar orange gradient. 

2. As we did our shopping, a player noticed that while all the other brands have a mechanical effect, Favored Primordia has the effect that it "charges the battlefield", which isn't nothing especially for Combos but doesnt really have mechanical weight, while Metalic Shout makes physical attacks "Rip and Tear", which a lot of them probably could already do, with no further bonus. If these were supposed to have mechanical weight like the others, it was not included.

3. A lot of missing info, mostly already addressed by me and others in the typos/eratta thread, most notably the game not really doing a great job at telling you where all your HP comes from.

As for things we discovered as a result of play:

1. While it seems like its intended that T2+ gear is supposed to come in a slow trickle, randomly generating gear as advised presented my table with tier 2 and 3 gear in the very first shop, and Tier 4 gear (which I had to ask what that did, since there's no rules for it) in the second. Now, Tier 4 gear is only a 1/36 (slightly higher? I have no idea if multiple Sales stack, which would add a tiny bit of odds of it happening on a T1 or T2) but when every single session is supposed to include shopping, and each shop is advised to have 10 items, you hit a 1/36 pretty quickly.  The high cost of T3 gear should make getting that gear probibitively difficult to get but...

2. Cash drops are really high! 3xTier is a lot even with a Tier 1 fight, but if any party members have +1 To Tier gear, that ramps up really fast. Session 2 resulted in a gain of 28 Cash per player when extra flow was included (that was not because they were saving flow either! One player has just specialized as the Flow Battery, stacking lots of +Flow effects), session 1 was only a little behind that even with us having not seen the flow = cash rule. They cleaned out all 10 items in the shop no problem with almost exactly half of the enemies rolling to drop cash. Youd think maybe I gave them too many enemies but...

3. Players output a lot of damage. With minions only dying in 1 hit (the rules say they "always" have 1HP, implying they dont get the HP bonus from their tier? If thats not the case, I feel like that needs clarified) and the ease of getting AOE attacks, and larger enemies being vastly outnumbered by the sheer number of player turns, it either means you have to throw massive numbers of enemies at players (thus getting them even more loot, see issue 2), or make them bulky slabs of HP to even begin to let them have a turn or two. Next session, I plan on throwing an encounter I expect to be way too hard at them in order to see if theyve just gotten too strong to stop after two sessions.

4. High level tokens are very good, and very easy to get. I didnt even notice until looking at the rules for this session that each player is supposed to roll for three tokens, not one, and even with one, and especially with Sticky Fingers and money being easy to get, rare and legendary tokents are super easy to acquire as soon as after the first encounter. Again, it feels like theyre supposed to he a slow trickle up the ranks and up in power, but with a combination of +Tier starting gear and decent rolls, almost all of my players had a  rare or legendary token immediately. l

5. All of this adds up to players being able to get very strong, very quickly, with no real way to ratchet up the difficulty with them that doesnt result in them getting even stronger even faster. A player went from 4HP fight 1, to 10 HP and the Core set bonus making them even tankier by the start of the second. 

6. Meanwhile, its either very hard or absolutely trivial to get a build you're aiming for. If someone in the party gets what you want, they can hand it over to you (and disabling this rule would be very awkward diagetically, what do you mean I can't hand someone a pin or a hat?), but if it just isn't rolled there isnt a lot you can do to make it show up. This results in players not really having control over their mechanics, even as they snowball out of control.

7. Lastly, its hard to justify players shopping after every fight diagetically. Its a thing the players want to do, because they can buy a bunch of cool clothing that balloons their stats. But why a group of players is splurging on new clothes every day is hard to justify, even the biggest fashion addict doesnt do that.

This is a game with a lot of promise based on my favorite game of all time. But part of what made that game great is the slow but constant growth in power. The growth of this game is fairly unchecked, and that turns a fairly strong core system (I genuinely love the flow system? Even as my players break it by having a player dedicated to generating as much flow as possible, I love it) into one thats so easy it quickly ceases to be fun as the players effortlessly clear every chalenge.

I appreciate you taking the time to write all this up! Gonna try and address each point best I can; 

1. Thanks for pointing that out! I'll make sure it gets filed for updating (unfortunately, some higher priority projects are currently ongoing, so I can't say when that update will happen). 

2. Copying the reply from another thread, but for both Favored Primordia and Metallic Shout, both those core bonuses are more narrative rather than hard mechanics: "For "rip and tear" its largely narrative! You might interpret it to mean that you now can rip through an enemy's armor or tear through a barrier. The exact effect is largely up to the table!" Those bonuses are more about setting up "fictional positioning" within the current situation vs some sort of stat bonus. They more directly benefit action rolls in that sense. 

3. HP source being hard to find is definitely a known issue 😩 . Hopefully you were able to find the answer, but just in case, HP all comes from the Looks you have equipped.

For the play questions!

1. Looks (and enemies, and everything else that references a Tier) cap out at Tier 3! Though nothing is stopping you from going higher with Tiers if you wanted! The only major thing that would need tweaking would be some specific Token effects, but otherwise Looks and Enemies could just keep scaling up (I think). 

2. Cash drops are high! Also like you pointed out, some builds (like the Flow stacker) can kind of break the game! That's pretty much working as intended. The LUMEN system that Vibe Check is running off of goes all in on the power fantasy, basically showering players in stuff. It's kind of the opposite of more "trad game" style of character progression. The sort of "philosophical goal" of most LUMEN games is to give the players the cool toys they want to play with upfront, and then see what happens!

3. This one's tricky! Players definitely can output a ton of damage very quickly when working together. You could try to throw some Bosses (using the templates) their way, to see if that changes anything, but also don't forget that on the GM Turn, you can also introduce more enemies! Additionally, there are other ways to create challenge outside of just enemy stats/density. Shifting the environment to become more dangerous or changing the mission type so that the players need to swap their tactics are good places to start. Also, are the players having fun wiping the floor with the enemies? Again, that kind of goes back to the wild power fantasy of LUMEN: lots of powerful toys. If the challenge aspect is really eating at you, I'd talk it over with your players and see what they think! If everyone agrees and wants more challenge, then bumping up enemy HP, decreasing cash drops (or increasing costs of everything instead) are fairly straightforward levels to adjust. If you're concerned about diagetically making those changes, well, maybe a Watcher isn't happy with how successful the Players have become and forces a reset!

4-6. This one kind of goes into the above response! If the players are having fun getting the cool loot, personally I don't necessarily see a drastic reason to change that, but if everyone wants more difficulty, then definitely adjust it! Every table is always going to be a little different in their goals. Also for the last part of 6, that concern does make sense! The intent of the random Tokens is to encourage players to always be trying out new strategies (and Looks). But if players are really wanting a specific Token and it just isn't coming up when rolling, then you can drop it in a store either to buy, or maybe as a side mission reward.

7. A little tongue in cheek, but they do do a lot of shopping in the TWEWY games 😆. But if you think that that doesn't make sense in your version of the Inversion, then absolutely change it! Could turn into an element of the narrative, like, maybe the shops are still open but the Players can't enter them. Now there's a new story hook to follow to see what has restricted their access!

TWEWY is also one of my favorite games of all time! Though I took inspiration from different elements, so the slower growth you're looking for isn't necessarily as hard-coded in Vibe Check. You mention that players effortlessly clearing the challenges isn't fun, and genuine question, are the players having fun doing that? It sounds like that no-challenge element is frustrating for you as the GM, which sucks! The GM needs to be having as much fun as the rest of the players! It's absolutely worth discussing this with your players to figure out the best way to adjust things so that everyone at the table is having fun. 

I'm always happy to talk about ways to "tweak some game settings" so to speak!

Thank you for such a detailed response! You asked a couple times if my players were having fun with the game being so easy, and that the answer is "no" is a big part of why I was driven to make this post in the first place. And the way things are going, the players are going to "max out" pretty quick, meaning even just the fun of Number Go Up is gonna fade after just a few sessions, especially with the confirmation that things max out at Tier 3 (which might need a note about what happens if you get a sale on a tier 3 item? A 1/36 chance of a thing happening the game just doesnt know how to happen in a thing being rolled 10 times a session is a lit). An RPG campaign is probably gonna total pretty close to the number of hours in TWEWY, and thats a long time if my players are maxed out so quickly. 

Edit: specifically about the set bonuses, that would be fine if all the set bonuses were narrative bonuses, but three of them have mechanical weight and two of them dont. Of the two, I think Favored Primorida is a bit better, in part because its a bit clearer what that actually does and in part because that's probably something you couldnt do without it. But I know my player who ended up with three Metalic Shout saw that and was disappointed compared to the player with three Quickened, who got to generate even more flow.

You're welcome! Bummer that the table isn't having fun with the current level of challenge though. The game is designed to be pretty over the top, kind of "here for a good time, not a long time", so super lengthy "traditional" campaigns may not be the best fit as-written right now (I see the campaign length as closer to 3-6 sessions, but each table is going to be different). I don't want this to come across as dismissive or anything, but right now the game is functioning as-designed (though I will admit the sale stacking issue is something that I completely overlooked😩), so there's only so much I can offer as suggestions!

That being said, there's nothing stopping your table from changing things within the game to try and align it better with what you're looking to get out of it. Off the top of my head, the easiest elements to adjust are enemy HP and the cost of items, if you're looking to draw out fights and make buying things more challenging. You can also increase the narrative stakes, but that's going to depend entirely on what's happening at your table, so I can't offer much in specific examples there unfortunately.

As for the Metallic Shout bonus, I think it's still fun! But if it feels "weak" you can also push what exactly "rip and tear" means. Why stop at something physical? Maybe with enough juice, a Player can rip and tear through the veil that separates the City and the Inversion itself? The effect is as strong as however you choose to interpret it. 

I sincerely hope that you can find the fun you're looking for in the game and I'm more than happy to keep discussing ways to tweak things to suit what you're looking for!